Tricia Stoll – Math Lesson Plans-November 2-6, 2015
Skill:Subtracting 2-digit numbers (Ready Common Core, Unit 2 – Lesson 8, pp. 70-79)
Skill for Review:Adding two digit numbers (Ready Common Core, Unit 2-Lesson7)
Monday
Standards / 2.NBT.B.5 Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.2.NBT.B.8 Mentally add 10 or 100 to a given number 100-900, and mentally subtract 10 or 100 from a given number 100-900.
Weekly Essential Questions / How can understanding place value help me add or subtract two-digit numbers?
Weekly I Can statements / I can add and subtract two-digit numbers with and without regrouping.
Bellringer / Introduce Math HW
Math Facts Drill
Read mathematical mission and vocabulary
LAB 12:00-12:30; 1:30-2:20
Anticipatory set / Flocabulary Place Value Video
Students will complete Lesson 8 Interactive Tutorial (teacher toolbox) Subtracting 2-digit numbers Level B (6 minutes)
with the teacher
Modeling / Use interactive manipulatives to model 74-28
Use the number line to model counting up and subtracting. Ask students to share what they remember from last week’s lesson. How are the arrows showing jumps on the first number line different from the arrows on the second number line? Students should notice that the arrows on the first number line jump to the right, or “go up” the number line. The arrows on the second number line jump to the left, or “go down” the number line. Students may also notice that each number line has a different number of jumps. 3 What does the direction of the arrows tell you about each number line? Because the arrows on the first number line go to the right, the first number line shows addition. Because the arrows on the second number line go to the left, the second number line shows subtraction.
Guided Practice / Students who completed 72-73 will work on i-ready, fluency, or hot dots.
• Remind students that they are trying to find a part of a whole. Girls + boys = children at camp. To find the number of boys, subtract the number of girls from the total: 54 2 27 5 ?, or add the number of boys to the number of girls: 27 1 boys 5 54.• Discuss how 27 is broken into 20 1 3 1 4 in both situations. Ask Mathematical Discourse questions 1 and 2 to reinforce use of these strategies. Discuss their value in performing mental calculations.
Mathematical Discourse
1 Why doesn’t it matter if you add up 20 first or 3 first?
2 Which way of adding up do you think is easiest to do in your head? Why?
Concept Extension Explore order when subtracting down. • Say: It doesn’t matter the order you use when adding up. What about when you subtract down? Is 54 2 20 2 7 the same as 54 2 7 2 20? Why? • Allow students to use connecting cubes and discuss their ideas in pairs before sharing with the class. Students should see that in both cases, they are subtracting a total of 27 cubes and that 20 1 7 is being subtracted, not 20 2 7. • Ask: Does 20 2 7 5 7 2 20? Explain. Make sure students understand that 20 2 7 does not equal 7 2 20, and have them justify their responses. Teacher Note: This subtraction problem can be modeled as 54 2 (20 1 7) or 54 2 (7 1 20), not 54 2 (7 2 20), in which case the subtraction in the parentheses would occur first.
TW review the vocabulary word regroupwith the students. TW introduce the word difference.
Independent Practice / SW work in the lab to complete i-Ready Math lessons. I-ready from 12-12:30, STmath from 1:30-2:15
Closure/Assessment / Windshield wipers to check for understanding of the lesson. Students will complete written closure. TW monitor students completing the guided practice and i-Ready Math lessons in the lab.
Tuesday
Standards / 2.NBT.B.5 Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.2.NBT.B.8 Mentally add 10 or 100 to a given number 100-900, and mentally subtract 10 or 100 from a given number 100-900.
Bellringer / Review Math HW-fluency drill Read mathematical mission and vocabulary
Complete Lesson 7 Quiz
LAB 12:00-12:30
Anticipatory set / Subtraction with Regrouping Rap
Lesson 8 Interactive Tutorial (teacher toolbox) Subtracting 2-digit numbers Level B (6 minutes)
Modeling / Students explore subtracting a two-digit number by decomposing a ten first and by subtracting tens first. Then students revisit this problem, evaluating the models and applying the strategies to a new problem. • Read the problem at the top of the page together as a class. Model It • Draw attention to Model It. Have students explain what the model shows. You may want to have base-ten blocks available for students to physically model, if necessary. • Ask: Why is one ten decomposed into ten ones? [It makes it easier to subtract 5 ones.] Model It • Have students evaluate the Model It picture. Ask: Why can we take away a ten first? [There are enough tens to subtract one ten.] • In the second step, a ten is decomposed to subtract 5 ones. Some students may prefer to subtract 5 from 32 by counting back 2 to 30 and another 3 to 27. There are many ways to think about subtraction, and this model is showing one of those ways.
Mathematical Discourse
Do you think it is easier to regroup a ten first or subtract tens first? Why? Students will have a variety of responses showing personal preference. Make sure all preferences are justified using mathematical reasoning and equally valued.
Guided Practice / Monitor while students complete page 75
Concept Extension Consider multiple strategies. • Have students review the subtraction strategies modeled on the previous two pages, which are used to solve the problem about camp, and the subtraction strategies modeled on these two pages, which are used to solve the problem about toy animals. • Ask: Why do you think the counting up strategy was used for the first problem and a take away strategy used for the second problem? Students may respond that the first problem is a part-of-the-whole problem, so it is like a number bond. You can think of the missing part as an addition or subtraction problem. The second problem is a take away situation, so it makes sense to model subtraction as taking something away. • Discuss with students that either strategy could be used in both situations. Have students talk in pairs about how they could use the “take away” strategy in the first problem and the “counting up” strategy in the second problem and then share their ideas with the class.
Independent Practice / Students will complete practice work. Teacher will evaluate progress.
Closure/Assessment / Concept Extension - Consider multiple strategies.
• Ask: Why do you think the counting up strategy was used for the first problem and a take away strategy used for the second problem? Students may respond that the first problem is a part-of-the-whole problem, so it is like a number bond. You can think of the missing part as an addition or subtraction problem. The second problem is a take away situation, so it makes sense to model subtraction as taking something away.
• Discuss with students that either strategy could be used in both situations. Have students talk in pairs about how they could use the “take away” strategy in the first problem and the “counting up” strategy in the second problem and then share their ideas with the class.
Wednesday
Bellringer / Review HWFluency practice Read mathematical mission and vocabulary
Anticipatory set / Subtraction with Regrouping video
Modeled/Guided Practice / Students use strategies to solve two-digit subtraction problems. • Ask students to solve the problems individually and show all their work, including the equations they wrote. Encourage students to describe their thinking. • Pair/Share When students have completed each problem, have them Pair/Share to discuss their solutions with a partner. Example An open number line is used to demonstrate the counting back strategy. Remind students that the jumps could be shown as 20 1 2 1 2. 14 Solution 23 pear trees; 90 2 60 5 30; 32 2 9 5 23. DOK 1
Independent Practice / Teacher/Teacher Assistant Groups
Begin CENTER ROTATIONS (20 minute rotations):
1)Teacher’s Table –
pp.76-77 Guided Practice: (high support group will be completed together with the teacher)
• Ask students to solve the problems individually and show all their work, including the equations they wrote. Encourage students to describe their thinking.
• Pair/Share When students have completed each problem, have them Pair/Share to discuss their solutions with a partner.
2)Mountain Language Set 6
3)Computers – i-Ready Math/ST Math
4)NEOS – Math Facts in a Flash
Independent- SW completepp. 83-36 Practice and Problem Solving from teacher toolbox.
Closure/Assessment / Windshield wipers to check for understanding of the lesson. TW monitor center activities to check for understanding.
Teacher will monitor as students work in centers. TW take independent work as a daily grade.
Thursday
Bellringer / Review HW fluency drills Read mathematical mission and vocabularyAnticipatory set / Flocabulary Place Value Video
Read Mathematical Mission
Modeled Instruction / TW model examples of 2-digit subtraction on the board.
Ask students to share all of the strategies presented in the workbook. Encourage them to use the workbook to find the strategies they used to subtract two digit numbers.
Guided Instruction / SW come to the board to help with examples using virtual manipulatives. Partners will work together to use various strategies for solving and checking work. EXPLAIN!!!!!
Independent Practice / Teacher/Teacher Assistant Groups
Complete Center rotations
Fluency center
Hot dots
Place Value work with team and select ways to model the problem
Math games
Independent 78-79
High Support
Hands-On Activity Use a hundreds chart to subtract two-digit numbers.
Materials: Activity Sheet 2 (Hundreds Chart), 1 counter • Distribute a hundreds charts and counter to each student and write the subtraction problem 63 2 27 on the board. • Tell students to find 63 on the chart and place the counter on it. Ask how they might use the chart to subtract 27. • Students subtract 27 by moving the counter vertically up the chart from 63 to 53 to 43 and then count back the additional 7. Color in the 27 squares that were subtracted. You may want students to use one color for the tens, another for the 3 ones subtracted to get to 40 and another color for the additional 4. • Repeat the process above using other problems involving subtraction.
Low support
Challenge Activity Devise a new subtraction strategy. Challenge students to think of a strategy for subtracting two-digit numbers that no one in the class has discussed yet. Tell them to: • Explain the strategy step-by-step so others can use it. • Test the strategy on three or four subtraction problems to make sure it works all the time.
• Give the explanation and a subtraction problem to a classmate to see if they can use the strategy. • Revise the strategy as needed so that it will work all the time and is explained clearly.
Closure/Assessment / Teacher will monitor as students work in centers. TW take independent work as a daily grade.
Complete written closure.
Friday
Bellringer / Math HeroesCheck HW Read mathematical mission and vocabulary
Anticipatory set / “Do My Best” motivational video
Procedures / SW complete Math Mixed Practice Test 2.3
Early finishers will work on any incomplete work in their math folders and work on ST Math or iReady Math.
Closure/Assessment / TW check MPT for an assessment grade.
Lesson 8 vocabulary
• regroup - to compose or decompose ones, tens, or hundreds.
For example, 10 ones can be regrouped as 1 ten, or 1 hundred can be regrouped as 10 tens.
• difference – the result of subtraction
Learning progression…
In Grade 1 students subtract within 20, recognizing when decomposing a number leads to a ten and utilizing addition to solve subtraction problems. Students subtract multiples of ten within 100 and mentally find 10 more or 10 less than a given number.
In Grade 2 students gain fluency adding and subtracting within 20. Students apply concepts of fact families as they explore how inverse operations can be a tool in solving addition and subtraction problems.
In this lesson students subtract a two-digit number from another two-digit number by counting back to a ten and by decomposing a ten. Students interpret picture models, number models, and open number lines to understand subtraction of two-digit numbers.
In Grade 3 students fluently add and subtract numbers within 1,000. They apply concepts of place value to division and recognize the role of subtraction in division with a remainder, and later in division of multi-digit numbers.